Common coaxial cable-based communication networks, for example, those applying the IEEE 802.4 communications standard, suffer from many drawbacks, including, for example, signal attenuation, tilt, group delay (also known as phase delay), jitter and slot time delay.
Signal attenuation affects the amplitude of the signal transmitted on a cable, and may affect the ability of a receiver to properly detect signals being transmitted on the cable. Tilt refers to the difference in amplitude between high frequency signals and low frequency signals due to higher attenuation of high frequency signals relative to low frequency signals. Group delay is a result of lower frequency signals travelling faster on cables than higher frequency signals. Group delay refers to the overlap of signals at a receiving end of the cable. Jitter refers to the timing uncertainty of the zero crossing of the received signal. Slot time delay is a parameter of a system that specifies the maximum time for a signal to be transmitted from any point in the system to another point and back again.
As cable communication networks grow larger, each of the above phenomena contribute to the degradation of transmitted signal integrity, thus increasing the likelihood of communication errors throughout the system. One known solution applied to extended cable-based communication networks is the use of so-called signal repeaters which are inserted at various points throughout the network. Such repeaters receive, amplify, and retransmit the signals being transmitted on the network. However, such repeaters are typically constructed from analog circuitry which, in many cases, actually exacerbates the problem of signal degradation. In addition, analog circuit-based signal repeaters can be susceptible to electromagnetic interference (EMI), and can suffer from drift due to aging and environmental sensitivity, all of which may introduce signal degradation. Microprocessor-based repeaters are also typically not acceptable because microprocessor program execution introduces unacceptable signal propagation delays through the repeater, thereby degrading the performance of cable-based communication network. Further, repeaters do not reconstruct transmitted signals, but simply amplify them along with any errors or anomalies in the signal. While simple signal amplification may correct for the affects of signal attenuation, it will not correct for tilt, group delay or jitter.
It would therefore be desirable to provide a repeater or network extender that combined the low propagation delay advantages of analog circuit-based repeaters with the accuracy of digital circuit-based repeaters without the disadvantages of either. It would also be desirable to provide a network extender that is capable of reconstructing a transmitted signal to correct for transmitted signal degradation.